EP0451069B1 - Bag made of heat sealable material and means for insuring its repeated closure - Google Patents

Abstract

Bag (1) for loose dry products, constituted by a parallelepipedal envelope made from heat-sealable material welded at its two ends (2) and (3), respectively the upper (2) and lower (3) ends, characterised: - in that the upper end (2) is welded along only a part (5) of its length; - and in that the non-welded part (6) of this end is closed by an adhesive strip (8). Application to the packaging of loose dry products, especially foodstuffs. <IMAGE>

Description

The invention relates to a bag of heat-sealable material for dry bulk products. It also relates to a device capable of ensuring the repeated closing of such sachets.

Many products, and in particular dry food products sold in bulk, are either in sachets made of transparent heat-sealable material, such as in particular plastic, or in cardboard packaging. Plastic bags, first made of viscose, then polypropylene, or even polyethylene, offer the advantage of being transparent, and therefore allow the buyer to view the product contained. However, this type of bag turns out to be difficult to open, the rupture line of the plastic being often random, sometimes leading to the opening of the packet in its length and thus leading the contents of the latter to spread out of control . In addition, these sachets are sometimes not very solid, thus presenting the drawback mentioned above.

Regarding cardboard packaging, although we no longer observe these drawbacks, namely the lack of robustness and the difficulty of opening, on the other hand, they generally prove to be less attractive to the buyer, given that it does not cannot view their content. In addition, they are generally of a higher cost price.

The invention aims to overcome these various drawbacks. It is aimed at a bag for dry bulk products which is simple and easy to open, without causing damage to the bag itself, and the contents of which are also poured in a simple and directed manner.

• en ce que l'extrémité supérieure est soudée sur une partie seulement de sa longueur ;
• et en ce que la partie non soudée de cette extrémité est fermée au moyen d'une bande adhésive.

This bag constituted by a parallelepipedic envelope of heat-sealable material welded at its two ends, respectively upper and lower, is characterized:

• in that the upper end is welded over only part of its length;
• and in that the non-welded part of this end is closed by means of an adhesive strip.

In other words, the invention consists in no longer traditionally welding the entire length of the upper end, but only weld the latter in part only, in order to define at the level of the non-welded part a zone which can be folded towards the inside of the bag and defining the pouring spout, making it possible to pour the contents of the bag in a directed and non-anarchic manner as this has so far been the case.

• l'extrémité supérieure est soudée sur la moitié au moins de sa longueur ;
• l'extrémité supérieure de l'enveloppe est repliée de chaque côté vers l'intérieur du sachet définissant ainsi deux plis symétriques, et la longueur de la partie non soudée de l'extrémité supérieure est légèrement supérieure à la longueur du pli correspondant replié vers l'intérieur, de sorte que le déploiement vers l'extérieur de ce pli, formant bec verseur, est toujours possible sans risque de souder ce pli avec l'extrémité supérieure lors de l'étape de soudure ;
• l'extrémité supérieure du sachet est repliée sur celui-ci, et la bande adhésive relie la portion non soudée de l'extrémité supérieure et le dessus du sachet ;
• le sachet est réalisé en polypropylène alimentaire transparent, mais on peut toutefois envisager l'utilisation d'une autre matière, telle que notamment le polyéthylène ou tout autre film d'emballage thermoscellable ;
• le sachet est destiné à renfermer des produits alimentaires secs et en vrac.

Advantageously, in practice:

• the upper end is welded over at least half of its length;
• the upper end of the envelope is folded on each side towards the inside of the bag thus defining two symmetrical folds, and the length of the non-welded part of the upper end is slightly greater than the length of the corresponding fold folded towards the inside, so that the outward deployment of this fold, forming a pouring spout, is always possible without risk of welding this fold with the upper end during the welding step;
• the upper end of the bag is folded over it, and the adhesive strip connects the unwelded portion of the upper end and the top of the bag;
• the bag is made of transparent food-grade polypropylene, but it is however possible to envisage the use of another material, such as in particular polyethylene or any other heat-sealable packaging film;
• the sachet is intended to contain dry and loose food products.

The invention also relates to a device able to allow the closure of the upper end of such a bag. This device basically comprises a pair of heating jaws, having an active toothed part, the length of which corresponds to the length of the upper end to be welded, associated with an inactive part devoid of any toothed element, corresponding at least to the length of the 'upper end not welded.

Advantageously, the inactive part receives a polytetrafluoroethylene (PTFE) insert, the thickness of which corresponds to that of the active part, and this for the purpose of pinching and gripping the upper end of the bag during the step of welding.

The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the example of embodiment which follows, given as an indication but not limiting in support of the appended figures.

Figure 1 is a schematic perspective view of a closed bag according to the invention.

Figure 2 is a schematic perspective view of the same bag in which the upper end is partially open.

Figure 3 is a schematic perspective view of the bag according to the invention in which the folds corresponding to the area of the upper end not welded are deployed outward to form the spout.

Figure 4 is a schematic perspective view of the closed bag according to the invention according to an improved embodiment.

Figure 5 is a plan view of a set of heating jaws of the device according to the invention in the operational position.

FIG. 6 is a view similar to that of FIG. 5, in which the inactive part of the jaws receives an insert made of PTFE.

In known manner, the bags of heat-sealable material for dry and bulk products are produced from a film of heat-sealable material which is positioned on a shaping device of appropriate shape, capable of giving it the definitive parallelepiped shape of the bag. First of all, a longitudinal edge-to-edge weld 4 is made of the two ends of the film. Then, the bottom of the bag is produced by closing the lower end 3 of said parallelepiped, and this, in a known manner by pinching between two heating jaws, at a temperature at least equal to the melting point of the plastic material. , simultaneously with the production of diametrically opposite folds, directed towards the inside of the bag, in order to obtain a relatively flat bottom.

The next step concerns the filling of the sachet, for example by means of metering devices which, in known manner, pour into the sachet a predetermined and calibrated quantity of bulk products.

The next phase concerns the closure of the upper end 2 of the bag, once it has been filled, carried out in a similar manner to the production of the bottom 3.

Advantageously, and with the exception of the first bag in a series, the upper end 2 of a bag 1 is closed simultaneously and the lower end 3 of the bag is closed. next bag. To do this, the station for carrying out this operation is in fact a double station, on which the upper bag is closed at its lower end 3 and receives the dry and bulk product from a metering device, and the full lower bag is closed at its upper end 2, the additional operation of separating the two bags made from the same film of heat-sealable material being carried out between the two sets of two welding jaws by means of a knife, guillotine type. In fact, the lower sachet is therefore filled when it is closed and then passes to the next stage called "packing", consisting in vibrating said sachet in order to slightly pack the bulk product in the package. In this way, taking into account these vibrations, an empty space is generated at the upper part of the bag, capable of allowing a less loose closure of the bag.

To do this, a pair of cold jaws, intended to produce the folds 7 at the level of the upper end of the bag 1 at this empty space, come to grip the bag at the level of it, and simultaneously, a knife performs a vertical incision to allow the air in this space to be released.

The following phase corresponds to the completion of the final weld of the upper end 2 by means of hot jaws, the weld being effected over at least half of the length 5 of the said upper end, but nevertheless less than the withdrawal zone. of the folded part 7 situated on the side of the non-welded part, in order to overcome any risk of welding of this said folded part 7. In fact, this folded part 7 subsequently plays the role of pouring spout by deploying it- this outward.

The next step then relates to the closing of the non-welded part 6 of the upper end 2 by means of an adhesive strip 8, glued for example by means of feelers on said part 6 to the upper part of the bag 1. Advantageously, this adhesive strip is provided on its sticky part with transfer glue capable of allowing the bag to be closed after each use. In addition, and in order to facilitate gripping of this strip, an area devoid of glue is provided at one of its ends, over a few millimeters.

In another embodiment, the adhesive strip 8 is permanently glued, the opening of the bag being effected by rupture of this strip. Once the strip removed, or torn, we take out the part folded 7 outwards, so as to form a spout as can be seen in FIG. 3. In this way, the pouring of the contents of the sachet 1 is carried out in a simple and easy manner in the desired direction and in quantity wanted. There is no longer any risk of damage or uncontrolled rupture of the sachet.

FIG. 4 represents an improved embodiment of the invention, in which the adhesive strip consists of a label 80 which covers most of the top of the bag 1 and which comprises a precut longitudinal strip 81 arranged astride the end upper 2 of bag 1.

The label 80 improves the finished appearance of the sachet, can carry various information relating to the product (and in particular a bar code) and prevents any risk of untimely tearing of the sachet at the level of the end 2.

The strip 81 facilitates the opening of the bag 1. It advantageously comprises a means making it possible to facilitate its lifting and tearing, such as a tab 81a projecting from one of the edges of the label 80.

The device capable of enabling the closure according to the invention to consist of, as can best be seen in FIG. 5, two complementary jaws 10 and 11, intended to cooperate with each other. Each of these two jaws is provided with a first zone 12 known as toothed active zone capable of allowing partial welding of the upper end 5 of the bag 1, and a second zone 13 known as inactive, devoid of any active zone so not to weld the corresponding part 6 of the upper end 2 of the bag.

In an advantageous embodiment shown in FIG. 6, this area 13 is filled with two pieces 14, attached by any appropriate means to the two jaws 10 and 11, and made of polytetrafluoroethylene, better known under the registered trademark "TEFLON", and the total thickness of these two parts corresponds to the thickness of the active part 12 of the jaws 10 and 11. In this way, the entire upper end 2 of the bag 1 is pinched laying the welding phase, without risk of adhering to this part 13. In addition, the choice of material used for this part is also dictated by the temperature conditions applied to said jaws 10, 11.

In this way, the sachets according to the invention prove to be quite easy to use and also simple to open, allowing rational payment of the contents. It is therefore entirely suitable for all bulk products, such as in particular food products, provided that a food-grade plastic material is used, such as for example polypropylene or polyethylene. This type of bag is therefore suitable for bulk products, for which vacuum storage is not necessary. These products can be in pulverulent form such as in particular flour, or even granular or others, for example pasta, rice, etc.

Claims (10)

1. Bag (1) for dry loose products comprising a parallel-epipid envelope made of heat-sealable material welded at its respective upper (2) and lower (3) extremeties, characterised:

   - in that the upper extremity (2) is welded for only a part (5) of its length;

   - and in that the non-welded part (6) of its extremity is closed by an adhesive tape (8).
2. Bag according to Claim 1, characterised in that the welded part (5) extends for at least half the length of the upper extremity (2).
3. Bag according to one of Claims 1 and 2, characterised in that the upper extremity (2) of the envelope is folded back on either side towards the interior of the bag (1), so as to form two symmetrical folds (7), and in that the non-welded part (6) is slightly greater than the length of the corresponding fold pointing towards the interior of the bag (1), intended to form a spout when it is unfolded outwards.
4. Bag according to one of claims 1 to 3, characterised in that the upper part (2) is folded back onto the bag (1), with the adhesive tape (8) joining the non-welded part (5) and the top of the bag (1).
5. Bag according to one of Claims 1 to 3, characterised in that the adhesive tape (8) is constituted from a label (80) which covers most of the top of the bag (1) and which comprises a pre-cut longitudinal tape (81) straddling the upper extremity (2) of the bag (1).
6. Bag according to Claim 5, characterised in that the tape (81) comprises means (81a) of facilitating its lifting and tearing.
7. Bag according to one of Claims 1 to 6, characterised in that it is made from transparent foodstuff-grade polypropylene.
8. Bag according to Claim 7, characterised in that it contains loose food products.
9. Device to close the upper extremity (2) of the bag (1) according to one of Claims 1 to 8, characterised in that it comprises heating jaws (10) and (11) presenting an active toothed part (12), linked to an inactive part (13) without teeth, the length of which corresponds to that of the non-welded part (6).
10. A device according to Claim 9, characterised in that the inactive part (13) receives an insert made of polytetrafluoroethylene (PTFE) the thickness of which is equal to that of the active toothed part (12).

Images